The proof is on the pudding, how performance critical do you consider Pluton firmware, network cards firmware supporting Azure workloads?
Two examples of stuff publicly rewritten into Rust.
Games are special that isn't what Windows security cares about in first instance, when TinyGlade is the first ever commercial success using Rust.
Yet most games are done with Unreal and Unity, and yes there is lots of C++ there, but is mostly Blueprints, Verse, C# on top, that large majority of studios reach for.
I have no magic window into Microsoft, but they've been saying they need to stop writing C++ for genuine decades now, and it's still prominent on their jobs site with new projects.
I'm aware they're trying, but I just don't believe their statements from the evidence available.